Containment has at least had one advantage: drastically reduce air pollution in Île-de-France, Airparif said on Friday. Between March 17, the date of confinement, and the end of April, ie ten days before deconfinement, the body noted a net reduction in pollution, in particular with nitrogen dioxide, a local pollutant mainly emitted by road traffic. The fall reached 20% to 35% depending on the week and up to 50% along the main roads.
“The impact is less for particles (PM10 and PM2.5), with a decrease of -7% which is explained by a strong influence of adverse weather conditions and by more sources of emissions, and not only local “, Also notes the association for monitoring air quality in Île-de-France. These particles are not only from road traffic, but also from heating, construction and agriculture, which had a "significant impact" during an episode of pollution in late March, said Airparif.
Falling ultrafine particles
The body has also studied the presence in the air of ultrafine particles (PUF, less than 100 nm, which can be as small as a DNA molecule), using a first station installed in the center from Paris, in the Halles district. The consequences of confinement were more significant on these PUFs, the surveys highlighting “a drop of around -30% for this type of particles, whose emissions are mainly linked to traffic (road, air) in built-up areas " The fall "is even greater on the range of the smallest ultrafine particles, namely less than 20 nanometers, with a drop of the order of 50%".
Airparif also points out that it will now “assess the consequences on air quality of the deconfinement (…), with changes that are more gradual than during confinement, which was sudden. Particular attention will be paid to the consequences of the increase in road traffic, the main source of air pollution in Ile-de-France and which has been gradually increasing over the past ten days without having regained the same intensity to date as 'before confinement'.
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